Due to recent developments of high-definition (HD) broadcasting equipment, trends towards an electronic cinema system, etc. in which movies are electronized, namely, conventional films are replaced by video tapes or the like have become active and make it necessary to deal with changes from a television field frequency of 60 Hz to a movie frame frequency of 24 Hz and from interlace (hereinafter, referred to as “i”) scanning method to progressive (hereinafter, referred to as “P”) scanning method.
A system for producing video signals electronically has a configuration which roughly includes an imaging device for obtaining, as imaging signals, 24P signals, i.e., progressive signals having the frame frequency of 24 Hz, a recording device for recording a rate of the 24P signals and a reproduction device for reproducing the 24P signals.
In HD video format, the 24P signals are standardized at a 1080-format having 1080 scanning lines and a 720P-format having 720 scanning lines by Society of Motion Picture and Television Engineers (SMPTE) 274M and SMPTE296M, respectively.
A prior art video signal producing system is shown in, for example, FIG. 35. In FIG. 35, “31” is an imaging device capable of outputting P imaging signals, “32” is a 24P recording device applicable to 24P and “33” is a reproduction device. Operation of the prior art video signal producing system of the above described arrangement is described below with reference to FIGS. 36 and 37. FIGS. 36 and 37 are wave form diagrams of wave forms a, b and c outputted from the respective devices of the video signal producing system shown in FIG. 35. Namely, “a” is an output signal of the imaging device 31, “b” is a signal recorded in the 24P recording device 32 and “c” is an output signal of the reproduction signal 33 for reproducing the signal recorded in the 24P recording device 32. Each numeral in FIGS. 36 and 37 denotes a frame number of each signal.
The imaging device outputs P imaging signals of frame rates of 24 Hz, 60 Hz, 48 Hz, 30 Hz, 20 Hz and 15 Hz indicated by (a1), (a2), (a3), - - - , (a6) of FIGS. 36 and 37, respectively. For example, (a1) of FIG. 36 is a case of the P imaging signal of the 24P frame rate. In this case, the recording device 32 performs recording at a recording speed of a one-fold value of the 24P frame rate in (b1) of FIG. 36. The reproduction device 33 also performs reproduction at a one-fold speed in (c1) of FIG. 36. Thus, a 24P signal which is an output signal of the so-called video signal can be obtained.
In 24P reproduction, reproduction of rapid feed or slow motion is necessary for stage effect in production of video signals in some cases. In case this production is performed, output rate of output of the imaging device 31 is changed and recording speed of the recording device 32 is changed accordingly, while the reproduction device 33 should perform reproduction at the one-fold value of the 24P frame rate. For example, slow motion reproduction of a (2/5)-fold speed is required to be performed, the imaging signal 31 outputs a 60P imaging signal as shown in (a2) of FIG. 36 and the recording device 32 records a signal at a recording speed of a (2/5)-fold value of the 24P frame rate as shown in (b2) of FIG. 36. Since the reproduction device 33 reproduces this signal at the one-fold speed, the signal of the original 60 frames is converted into a signal of 24 frames and thus, a video signal of slow motion of the (2/5)-fold speed is obtained from (24/60=2/5). Likewise, a case in which the imaging device 31 outputs a 48P signal is shown in (a3), (b3) and (c3) of FIG. 36 and a case in which the imaging device 31 outputs a 30P signal is shown in (a4), (b4) and (c4) of FIG. 37.
Meanwhile, in case rapid feed reproduction is required to be performed, the imaging signal 31 outputs an imaging signal slower than 24P, e.g., a 20P imaging signal as shown in (a5) of FIG. 37 and the recording device 32 records a signal at a recording speed of a (6/5) value of the 24P frame rate as shown in (a6) of FIG. 37. Since the reproduction device 33 reproduces this signal at the one-fold speed, the signal of the original 20 frames is converted into a signal of 24 frames and thus, a video signal of rapid feed is obtained. Similarly, a case in which the imaging device 31 outputs a 15P signal corresponding to a (24/15)-fold speed is shown in (a6), (b6) and (c6) of FIG. 37.
Thus, in the prior art video signal producing system, the ordinary 24P video signals and the 24P video signals of slow motion and rapid feed can be produced.
However, in the prior art video signal producing system referred to above, the ordinary 24P video signals and the 24P video signals of slow motion and rapid feed can be produced but recording speed of the recording device is required to be changed in accordance with output rate of the imaging signal of the imaging device, thereby resulting in increase of its circuit scale and electric power. Therefore, in case an imaging device and a recording device are incorporated in, for example, a VTR built-in imaging device, such drawbacks are incurred that the incorporation is difficult due to difficulty in more compactness and lower electric power.
On the other hand, FIG. 38 shows an arrangement example of a video signal recording and reproducing apparatus in a conventional video signal producing system. Meanwhile, FIG. 39 is a conceptual view of signal wave forms of respective portions of prior art. In FIG. 39, “A”, “B”, “C” and “D” correspond to signals A, B, C and D in FIG. 38 and “F1”, “F2”, - - - denote video signals of one frame, respectively. The conventional video signal recording and reproducing apparatus of the above described arrangement is described with reference to FIGS. 38 and 39. In case an imaging unit 901 performs imaging by 24P signals, recording and reproduction can be performed directly without frame rate conversion of the 24P signals, etc. as shown in FIG. 39A if a recording unit 103 and a reproduction unit 105 correspond to recording and reproduction of the 24P signals. One frame of the 24P signals reproduced after editorial processing is printed on one frame of a film by a kinescope recording (kineco) device as it is.
In case the imaging unit 901, the recording unit 103 and the reproduction unit 105 correspond to 60P signals (progressive signals having a frame rate of 60 Hz) such that the progressive signals have a frame rate twice that of, for example, current SD television signal format or HD television signal format, the 24P signals are generally obtained by periodically extracting intermediate frames from consecutive frames in the reproduction unit 105 as shown in FIG. 39B and are printed on the film.
Furthermore, in order to replace film shooting by electronic video recording using a video camera and a VTR or a hard disc apparatus, it is essential to materialize slow motion in which shooting is preliminarily performed by running the film at a speed higher than an ordinary one and the film is run at the ordinary speed during projection and, on the contrary, high-speed motion in which shooting is preliminarily performed by running the film at a speed lower than the ordinary one and the film is run at the ordinary speed during projection. In response to this demand, a multi-frame-rate type imaging device in which frame rate at the time of imaging can be set to an arbitrary value by controlling a charge coupled device (CCD) drive method of an imaging portion is proposed.
However, in the above described conventional video signal recording and reproducing apparatus, in case slow motion or high-speed motion is materialize at a simple ratio, for example, recording is performed at a frame rate of 48P (progressive signals having a frame rate of 48 Hz) and reproduction is performed at 24P or recording is performed at 12P (progressive signals having a frame rate of 12 Hz) and reproduction is performed at 24P, this can be easily done in the case of, for example, a VTR by manually setting a special reproduction jog dial to a (1/2)-fold speed or a 2-fold speed during reproduction. However, in case more delicate speed control is attempted, for example, in shooting of a scene of a ship cruising on the sea, a miniature ship is shot by beforehand raising film speed and motion of the ship is displayed more dynamically by running the film at the ordinary speed during reproduction or on the contrary, in order to display a boxing scene more fiercely, shooting is performed by preliminarily lowering film speed slightly and an actor's action is made rapid to such a degree as to eliminate unnaturalness by running the film at the ordinary speed during reproduction, such cases may happen in which set speed obtained by manual setting of the jog dial of the VTR is not continuously variable, adjustment to a desired predetermined speed cannot be performed and high accuracy in reproduction speed cannot be obtained.